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Garethr

Constant damp weather

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Garethr    276

Hi Guys, 

Anyone else noticed any issues with this continual wet weather.  Went to roll back my Obsy roof the other day as a check and found the catches very stiff.  As I have a RORO roof I was a bit concerned at this but not sure what to do about it.

I appreciate that this design will always allow a certain amount of moisture to "get to the timbers" but I was suprised to see such a noticeable difference when I released the catches.  Obviously no point in turning up the heaters to dry it out as this will be heating up Buckinghamshire to no avail.  Any thoughts all?

Gareth

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steppenwolf    4,632

Sadly, I take the view that de-humidifying half of West Sussex is worth the cost as my observatory and its contents remain nice and dry at all times. If you do decide to take this route, make sure that you buy a desiccant dehumidifier rather than a refrigerant type as the latter do not work well at low temperatures.

Yet another expense but well worth it for both comfort and ensuring the long-term reliability of your gear.

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ChrisLX200    3,594

I also run a de-humidifier, too much expensive stuff to allow it to rust/go mouldy... You don't have to run it when your Obs is open, and if you plug the big gaps it will be quite effective. I keep mine set to 60% humidity which is dry enough, and it cuts out when that target is reached.

ChrisH

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Garethr    276

It's the scope room and roof that suffers .

In the warm room I have an electric heater in that sits at 5 degrees as protection against frost and keeps the warm room dry.

Gareth.

Edited by Garethr

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Garethr    276

Steppenwolf and Chris,

Not sure a dehumidifier would work for me as it's RORO roof it lets air through.

Surely this would be working 24/7 and not achieving anything?

Gareth 

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steppenwolf    4,632

My domed observatory is still open to the outside air via the lip of the dome that fits inside the wall, hence my comment about 'de-humidifying half of West Sussex' but by its very nature, the observatory will have its own micro-climate and this is where most of the hard work is done by the dehumidifier!

As Chris says, 'too much expensive stuff to allow it to rust/go mouldy...'

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Astroboffin    163

As long as you have very good ventilation, and your obsy is fully waterproof, you should not need anything, as any cold damp air will not condense, as the constant airflow will stop that, and the temperature inside the obsy will only be a small amount above the outside temp.

The downside is that when you want to sit in there it will be very cold at certain times of the year.

I think the biggest problem is people use heaters while in there obsy, then when they have finished for the night, they turn them off and close up and go indoors for the night, the warm air then left in the obsy will then condense on the inside of the roof and walls because of the cold outside temp, then this will run down and cause damp, then when the moisture gets down on the floor where it is cold, it will turn to vapour and rise and condense again, and so it goes around and around.

So the secret is lots of good ventilation, and no leaks, and all should stay dry and mould free.

Well it works perfectly in my hole ridden shed, which is watertight but full of ventilation...and my tools have never had any rust or damp on them, and never had heat or a dehumidifier in there in 10 years.

Sorry for the ramble, but it does work.

AB. :) :)

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Gina    9,312

I have a desiccant type dehumidifier running all the time but it cuts out automatically when the humidity gets low enough.  OTOH I have brought a lot of gear indoors.

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Ibbo!    4,851

when I think about it I have one of those tube heaters 10w I think

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Tinker1947    2,127

I have a Polycarbonate roof, opened the Obby this afternoon, dry as a bone, the Rubber roof it replaced used to be dripping wet.......

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Stub Mandrel    6,363

This is a topic regularly debated by workshop owners. The time that causes problems is when the air is fairly humid, it is cold and then things warm up differentially. Soggy woodwork can then warm and release a lot of moisture that then condenses on bare metal that is still cold as it isn't in contact with the outside. This means the early morning is the high-risk time.

Dehumidifiers work, but can't always keep up in severe conditions. Gentle heating (some people fit small 50W heaters to lathes etc.) is effective.

My solution is draught proofing (but not airtight!), damp barriers lining the walls and insulation - I have had about three things develop rust in my workshop over 14 years, and I just have a heater on 'frost'.

<wish I could spill properly>

Edited by Stub Mandrel

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Macavity    3,153

I still get dampness permeating the floor close to the walls. But my

observatory was pre-built. I note some (probable) design flaws. :o

(I have installed (sticky!) "flashing" all around the base / walls). 

But if you can, have a supporting concrete raft (paving) *smaller*

than the walls? Have the floor "suspended" within the walls, rather

than as the base for the whole shebang. But retrospect is easy? :p

I know naaathing, but I do wonder if one can realistically maintain

an outdoor "unsealed" outdoor structure *entirely* moisture free? 

I sense it might be easier / cheaper to allow some air circulation...

But then, I do all my stuff via remote control, these days...

I would be seriously thinking of a "mini" observatory (box). :D

Edited by Macavity

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Astroboffin    163

The whole point of no damp is loads of air circulation.....one day people will realise that ventilation is the key to NO damp....:)

Forget all the other thing like spending money on heaters or dehumidifiers it is a waste of money, just ventilate the room.....have a good constant airflow in and out.....and it will look after itself..

AB

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Tinker1947    2,127

My workshop, is built with celcon blocks 18"x 9" x 9" 25' long 16' feet wide, the inner walls have polystyrene sheets covered with 9mm sterling board, the roof from the outside inwards, 9" x 6" concrete tiles, felt, 3/4" ply, 4" of fiber glass,  1/4 ply attached to the A Frames, the floor is concrete, pair of 4' X 8' 3/4 ply on timber frames insulated with sterling board on the inside 2" of Polystyrene sheet in between, heat is supplied by a log burner been lite twice since last winter, on one of the walls there are 8 Chisels not coated in anything there shine steel and have been for the 14 years they have been there, it never smells damp, decent insulation is all it has, Obby's are a totally different thing....

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gnomus    2,828

My domed observatory is still open to the outside air via the lip of the dome that fits inside the wall, hence my comment about 'de-humidifying half of West Sussex' but by its very nature, the observatory will have its own micro-climate and this is where most of the hard work is done by the dehumidifier!

As Chris says, 'too much expensive stuff to allow it to rust/go mouldy...'

I have the same dehumidifier as you Steve. I have tried runnng it at 60% 24/7. What I found is that it would fill up within a day or so and need emptying. How often do you have to empty yours?

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ChrisLX200    3,594

I have the same dehumidifier as you Steve. I have tried runnng it at 60% 24/7. What I found is that it would fill up within a day or so and need emptying. How often do you have to empty yours?

I have mine plumbed direct to the outside, it's the only sensible option.

ChrisH

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Bizibilder    4,419

My wooden observatory is a s dry as a bone inside - Just been to look after not using it for nearly six weeks!  I have a decent air gap around the base of the ROR (about 3cm all round) which allows some air circulation.  No heater or dehumidifier used at all.

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Astroboffin    163

My wooden observatory is a s dry as a bone inside - Just been to look after not using it for nearly six weeks!  I have a decent air gap around the base of the ROR (about 3cm all round) which allows some air circulation.  No heater or dehumidifier used at all.

That's the way to do it.......

:)

AB

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rubecula    65

Interesting topic.  I was thinking of starting a similar post.  I have the ELA DD822 in a Pulsar fibreglass observatory.  Over the last couple of weeks I've been getting over a container full of water per day when running the dehumidifier at 60% humidity. 

I'm not keen on drilling a hole in the obsy wall for the constant drainage tube and can't see how to get ventilation in such an observatory so will have to keep baling it out with the dehumidifier.

Robin

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steppenwolf    4,632

I'm not keen on drilling a hole in the obsy wall for the constant drainage tube and can't see how to get ventilation in such an observatory

I really wouldn't worry too much about that, a cheap hole cutter and a little filing makes the job simple and won't harm the observatory at all and you can then use a right angled waste connector to make a neat exit to the outside.

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rubecula    65

I really wouldn't worry too much about that, a cheap hole cutter and a little filing makes the job simple and won't harm the observatory at all and you can then use a right angled waste connector to make a neat exit to the outside.

Steve, I presume you are pushing the plasic tube that comes with the dehumidifier through the bent tank connector and then taking the tube over the edge of the concrete slab. 

I wouldn't want to discharge the water onto the slab as it would run back into the observatory and end up constantly going round in circles. :laugh: :laugh:

Robin

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steppenwolf    4,632

Steve, I presume you are pushing the plasic tube that comes with the dehumidifier through the bent tank connector and then taking the tube over the edge of the concrete slab. 

My thin silicone tubing (supplied with the dehumidifier) runs into the outlet I linked to above with a few inches of the tubing running into standard 22mm waste pipe which runs to the edge of the slab where a 90 degree joiner flips over the edge with a small length of piping to act as a downpipe. The collected water is taken away from the observatory completely.

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Gina    9,312

Same here.  And I live on the side of a hill so water drains down the fields to the river several hundred feet below :D

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tteedd    10

I put together my second hand old style Pulsar observatory in the summer.

Very pleased that I did not seem to need my dryer anymore.

Went away at the end of September and came back on 17 November. Equipment and observatory fine. Used twice in November but then not used until last night due to poor conditions and a heavy cold.

Clear last night after the festivities, so opened up. First thing I noticed was that the shroud over the scope was wet. Then found everything else was wet with condensation running down the dome. Secondary mirror hazy and did not clear with the dryer (did not seem to affect performance much - but I will find out when the moon has gone).

Today I have bought a cheap de-humidifier which I am running on a long lead from the house (only have 12V in the obs').

Long term I do not know. I do not fancy putting lots of ventilation in the observatory. Taking the scope out negates the very reason for having the observatory in the first place (being able to observe at the drop of a hat).

Suggestions from anyone with a similar observatory would be welcome.

Happy new year

Ted

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